New here and have a problem and need help. I have 1998 Suburban with 4wd, 190K miles and front/rear climate control. The compressor clutch engages and disengages in 3 second intervals so needless to say the a/c is not blowing cool air. The rear climate control is not working (fan switchset tooff or on high and the fans blow at the same rate). Pressure checks show 40 low and 70 high. Any ideas on what is going on. I appreciate any help you can give.

 

This thing happens when engine idle speed is too low,try to clean throtle body (if equiped ) oradjust idle speed.Or there is insufficient gas in the system.high side pressure is too low it should show 150 psi. If any mistakes correct me.

 

take the truck in to have it checked for leaks....have them pull the freon out to see how much is left in the system and top it up as neccessary and add some dye to the system so when it gets low again, they can check with a UV light to find the leak